Measure out and prepare all the ingredients. Preheat oven to 450F.

Line a baking sheet with parchment paper.

Slice the cabbage in half then into smaller slices, making the "dough" of the pizza. Drizzle with olive oil and season with salt and pepper. Roast these in the oven for 15 - 20 minutes.

Chop up the green onions and the corned beef.

Once the cabbage is ready to take out of the oven, smear the whole grain mustard onto the cabbage pieces. Top with corned beef and shredded cheddar cheese. Bake in the oven for about 5 minutes just until the cheese is melted.

Garnish with green onions. Serve and enjoy!